Syringes are commonly used for the delivery of fluids in the medical field and are oftentimes adapted to syringe pumps in order to attempt to deliver fluids at a constant volumetric rate. Typically, as smaller dispensing volumes with greater precision are desired, syringes with smaller diameter barrels are used in order to decrease the cross-sectional area of the fluid being forced out of the syringe by the plunger. The smaller the cross-sectional area of fluid within the syringe barrel, the smaller the volume of fluid that will be dispensed when the plunger is advanced a given distance. Therefore, to achieve the delivery of increasingly smaller volumes of fluid (e.g. fractions of a microliter), it is necessary for the syringe plunger to advance in increasingly shorter distances.
It is typically the case with pulse modulated syringe pumps that the plunger is unable to advance in small enough increments so that a series of small boluses (e.g. fractions of a micro liter) average out to a desired low flow rate. In such cases where a pulse modulated syringe pump is unable to advance in small enough increments, the remedy is oftentimes delivering larger volumes (boluses) of fluid less frequently so that over a period of time the desired flow rate is achieved. Negative outcomes can result from delivering some medications to patients in significantly larger boluses than the recommended drug delivery rate. Additionally, it is increasingly difficult to move a syringe plunger at increasingly shorter distances due to the difficulties associated with the plunger having to overcome sticktion (static friction). It is well known to those skilled in the art that the fluid sealing portion of the plunger has to overcome the friction of the seal by initially requiring a greater force than what is necessary to advance the plunger once the plunger has begun to advance. Therefore, it becomes increasingly difficult to control increasingly shorter advancements of a plunger and achieve high dispensing volume precision.